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Search Results: 1 - 10 of 32084 matches for " Ana Obeso "
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Tetrodotoxin as a Tool to Elucidate Sensory Transduction Mechanisms: The Case for the Arterial Chemoreceptors of the Carotid Body
Asuncion Rocher,Ana Isabel Caceres,Ana Obeso,Constancio Gonzalez
Marine Drugs , 2011, DOI: 10.3390/md9122683
Abstract: Carotid bodies (CBs) are secondary sensory receptors in which the sensing elements, chemoreceptor cells, are activated by decreases in arterial PO 2 (hypoxic hypoxia). Upon activation, chemoreceptor cells (also known as Type I and glomus cells) increase their rate of release of neurotransmitters that drive the sensory activity in the carotid sinus nerve (CSN) which ends in the brain stem where reflex responses are coordinated. When challenged with hypoxic hypoxia, the physiopathologically most relevant stimulus to the CBs, they are activated and initiate ventilatory and cardiocirculatory reflexes. Reflex increase in minute volume ventilation promotes CO 2 removal from alveoli and a decrease in alveolar PCO 2 ensues. Reduced alveolar PCO 2 makes possible alveolar and arterial PO 2 to increase minimizing the intensity of hypoxia. The ventilatory effect, in conjunction the cardiocirculatory components of the CB chemoreflex, tend to maintain an adequate supply of oxygen to the tissues. The CB has been the focus of attention since the discovery of its nature as a sensory organ by de Castro (1928) and the discovery of its function as the origin of ventilatory reflexes by Heymans group (1930). A great deal of effort has been focused on the study of the mechanisms involved in O 2 detection. This review is devoted to this topic, mechanisms of oxygen sensing. Starting from a summary of the main theories evolving through the years, we will emphasize the nature and significance of the findings obtained with veratridine and tetrodotoxin (TTX) in the genesis of current models of O 2-sensing.
Cuando una acción ya no es necesaria: La importancia de la inhibición
Ignacio Obeso
Ciencia Cognitiva : Revista Electrónica de Divulgación , 2011,
Abstract: funciones ejecutivas, inhibición, Parkinson.La inhibición conductual, la capacidad de detener acciones en curso, es una función importante para lasupervivencia humana. Esta capacidad está alterada en diversas enfermedades, como la enfermedad deParkinson. donde se observa una mayor dificultad para inhibir acciones. Datos recientes ayudan a aclarar elsustrato neural de una función tan importante como la inhibición.
Dimensional regularization of Schrodinger Functional correlation functions
Eduardo Obeso
Physics , 2005,
Abstract: The matching between Schrodinger Functional renormalization schemes and conventional perturbative schemes is usually done using an intermediate lattice scheme. We propose to do the matching directly. This requires the perturbative evaluation of Schrodinger Functional correlation functions in the continuum. We use dimensional regularization but due to the lack of translational invariance in the Euclidean time direction, we employ a general technique introduced by Luscher. In this talk I describe this technique and its application to the one-loop expansion of correlation functions used in the definition of the renormalized quark mass in the Schrodinger Functional scheme. The divergent parts are identified and the computation of finite parts is in progress.
Fernando de Castro and the discovery of the arterial chemoreceptors
Constancio Gonzalez,Teresa Gallego-Martin,Maria Ramirez,Maria T. Agapito,Angela Gomez-Ni?o,Ana Obeso,Asuncion Rocher
Frontiers in Neuroanatomy , 2014, DOI: 10.3389/fnana.2014.00025
Abstract: When De Castro entered the carotid body (CB) field, the organ was considered to be a small autonomic ganglion, a gland, a glomus or glomerulus, or a paraganglion. In his 1928 paper, De Castro concluded: “In sum, the Glomus caroticum is innervated by centripetal fibers, whose trophic centers are located in the sensory ganglia of the glossopharyngeal, and not by centrifugal [efferent] or secretomotor fibers as is the case for glands; these are precisely the facts which lead to suppose that the Glomus caroticum is a sensory organ”. A few pages down, De Castro wrote: “The Glomus represents an organ with multiple receptors furnished with specialized receptor cells like those of other sensory organs [taste buds?]…As a plausible hypothesis we propose that the Glomus caroticum represents a sensory organ, at present the only one in its kind, dedicated to capture certain qualitative variations in the composition of blood, a function that, possibly by a reflex mechanism would have an effect on the functional activity of other organs… Therefore, the sensory fiber would not be directly stimulated by blood, but via the intermediation of the epithelial cells of the organ, which, as their structure suggests, possess a secretory function which would participate in the stimulation of the centripetal fibers”. In our article we will recreate the experiments that allowed Fernando de Castro to reach this first conclusion. Also, we will scrutinize the natural endowments and the scientific knowledge that drove De Castro to make the triple hypotheses: the CB as chemoreceptor [variations in blood composition], as a secondary sensory receptor which functioning involves a chemical synapse, and as a centre, origin of systemic reflexes. After a brief account of the systemic reflex effects resulting from the CB stimulation, we will complete our article with a general view of the cellular-molecular mechanisms currently thought to be involved in the functioning of this arterial chemoreceptor.
Rese a de "Cultura y tradición oral en el Caribe Colombiano" de álvaro Baquero Montoya y Ada De la Hoz Siegler
Rafaela Vos Obeso
Memorias: Revista Digital de Historia y Arqueología desde el Caribe , 2011,
Abstract:
Carotid body, insulin, and metabolic diseases: unraveling the links
Sílvia V. Conde,Joana F. Sacramento,Maria P. Guarino,Constancio Gonzalez,Ana Obeso,Lucilia N. Diogo,Emilia C. Monteiro,Maria J. Ribeiro
Frontiers in Physiology , 2014, DOI: 10.3389/fphys.2014.00418
Abstract:
Temporal Characterization of Homology-Independent Centromere Coupling in Meiotic Prophase
David Obeso,Dean S. Dawson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010336
Abstract: Over the past thirty years several reports of the pairing or association of non-homologous centromeres during meiotic prophase have appeared in the literature. Recently, the homology-independent pairwise association of centromeres, termed centromere coupling, was also reported in budding yeast. It seems paradoxical that centromeres would pair with non-homologous partners during a process intended to align homologous chromosomes, yet the conservation of this phenomenon across a wide range of species suggests it may play an important role in meiosis.
Multilevel Selection and Neighbourhood Effects from Individual to Metapopulation in a Wild Passerine
Paola Laiolo, José Ramón Obeso
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038526
Abstract: Multilevel selection has rarely been studied in the ecological context of animal populations, in which neighbourhood effects range from competition among territorial neighbours to source-sink effects among local populations. By studying a Dupont’s lark Chersophilus duponti metapopulation, we analyze neighbourhood effects mediated by song repertoires on fitness components at the individual level (life-span) and population level (growth rate). As a sexual/aggressive signal with strong effects on fitness, birdsong creates an opportunity for group selection via neighbour interactions, but may also have population-wide effects by conveying information on habitat suitability to dispersing individuals. Within populations, we found a disruptive pattern of selection at the individual level and an opposite, stabilizing pattern at the group level. Males singing the most complex songs had the longest life-span, but individuals with the poorest repertoires lived longer than ‘average’ males, a finding that likely reflects two male strategies with respect to fitness and sexual trait expression. Individuals from groups with intermediate repertoires had the longest life-span, likely benefitting from conspecific signalling to attract females up to the detrimental spread of competitive interactions in groups with superior vocal skills. Within the metapopulation selection was directional but again followed opposite patterns at the two levels: Populations had the highest growth rate when inhabiting local patches with complex repertoires surrounded by patches with simple repertoires. Here the song may impact metapopulation dynamics by guiding prospecting individuals towards populations advertising habitat quality. Two fitness components linked to viability were therefore influenced by the properties of the group, and birdsong was the target of selection, contributing to linking social/sexual processes at the local scale with regional population dynamics.
Dimorfismo sexual en el acebo, Ilex aquifolium: ?coste de la reproducción, selección sexual o diferenciación fisiológica?
OBESO,JOSé RAMóN; RETUERTO,RUBéN;
Revista chilena de historia natural , 2002, DOI: 10.4067/S0716-078X2002000100007
Abstract: three hypotheses were examined in order to explain the existence of sexual size dimorphism in the dioecious tree ilex aquifolium (aquifoliaceae): cost of reproduction, sexual selection (pollen competition) and physiological differentiation between sexes. here we present both published and new experimental and observational results. at flowering, males allocated more in reproduction than females; however at fruiting females allocated about ten times more in terms of carbon and about five times more in terms of nitrogen than males. both sexes did not differ in leaf dynamics. branch rgr usually showed greater values in male branches, but the results depended on the ecological context. tree growth rate, estimated from mean width of annual rings over 10-30 yr, was significantly higher for males. experimental debbuding in reproductive branches of females accounted for an increase in rgr compared to branches that matured fruits. when competition among males was examined, there were significant differences among male trees in pollen production per flower. the experimental crossing of five males and five females demonstrated strong maternal effects on fecundity, while non significant differences among males were found in their probability of sire progeny. there were some physiological differences between sexes. the efficiency of photosynthesis of leaves (measured as fv' / fm') on nonfruiting branches of females was higher than for leaves on branches of male trees under low-light conditions. on the other side, the water-use efficiency, measured by carbon isotope discrimination, was greater in males under xeric conditions. these results are used to discuss the importance of the above mentioned hypothesis
Dimorfismo sexual en el acebo, Ilex aquifolium: coste de la reproducción, selección sexual o diferenciación fisiológica? Sexual dimorphism in holly Ilex aquifolium: cost of reproduction, sexual selection or physiological differentiation?
JOSé RAMóN OBESO,RUBéN RETUERTO
Revista chilena de historia natural , 2002,
Abstract: Se examina la importancia de tres hipótesis que pueden explicar la existencia de dimorfismo sexual en caracteres secundarios (tama o) en árbol dioico Ilex aquifolium (Aquifoliaceae): coste de la reproducción, competencia entre machos y diferenciación fisiológica entre sexos. Para ello se presenta una síntesis de trabajos publicados junto con nuevos resultados de tipo observacional y experimental. Durante la floración los machos invirtieron el triple de carbono y el doble de nitrógeno que las hembras. En la fructificación, los árboles hembras invirtieron 10 veces más que los machos en carbono, pero sólo cinco veces más en nitrógeno. No se encontraron diferencias entre sexos en la dinámica foliar y las diferencias en el crecimiento de las ramas fueron dependientes del contexto, aunque en general crecieron más en los machos. En periodos de tiempo largos, 10-30 a os, el grosor medio de los anillos de crecimiento de los árboles fue superior en los machos. Las ramas en las que se interrumpió la reproducción eliminando los brotes florales crecieron significativamente más que aquellas que maduraron frutos. Se encontraron diferencias entre machos en la producción de granos de polen por flor. La realización de todos los cruces posibles entre cinco machos y cinco hembras demostró fuertes efectos maternos en la fecundidad, pero no hubo diferencias entre machos en la probabilidad de dejar descendencia. Existen diferencias fisiológicas entre sexos en condiciones de baja luminosidad; así la eficiencia de la fotosíntesis (evaluada como Fv' / Fm') fue mayor en las hembras y por el contrario, los machos fueron más eficientes en el uso del agua (evaluado mediante discriminación isotópica del carbono). Finalmente se discute la importancia de las hipótesis consideradas para explicar estos resultados Three hypotheses were examined in order to explain the existence of sexual size dimorphism in the dioecious tree Ilex aquifolium (Aquifoliaceae): cost of reproduction, sexual selection (pollen competition) and physiological differentiation between sexes. Here we present both published and new experimental and observational results. At flowering, males allocated more in reproduction than females; however at fruiting females allocated about ten times more in terms of carbon and about five times more in terms of nitrogen than males. Both sexes did not differ in leaf dynamics. Branch RGR usually showed greater values in male branches, but the results depended on the ecological context. Tree growth rate, estimated from mean width of annual rings over 10-30 yr, was significantly higher
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